Field of the Invention
The present invention relates to a cutting apparatus for cutting a wafer formed with a low-k film on a front side thereof so as to divide the wafer into individual chips.
Description of the Related Art
In recent years, for enhancing processing capability of devices such as ICs and LSIs, a wafer provided on a front side thereof with a laminate adopting a low dielectric constant insulator film (low-k film) as an interlayer dielectric film has been put to practical use. This type of wafer is divided into individual device chips, before being utilized for a variety of electrical apparatuses such as mobile phones and personal computers. In relation to dividing the wafer formed with a low-k film on the front side thereof, there has been proposed a method of dividing a wafer into individual chips wherein grooves are formed in the low-k film along division lines by grooving by irradiation with laser (laser grooving) (the grooves thus formed by grooving will hereinafter referred to as “grooving grooves”), and a cutting blade is made to cut the wafer along the grooving grooves, thereby dividing the wafer into the individual chips (see, for example, Japanese Patent Laid-open No. 2005-064231).
Side surface portions of each grooving groove thus formed by cutting of the low-k film are very brittle. When the cutting blade is made to cut into the wafer along the grooving groove, therefore, the cutting blade may come into contact with the low-k film present at each side surface of the grooving groove to cause peeling of the low-k film, thereby possibly damaging the devices. For avoiding the contact of the cutting blade with the low-k film, therefore, a method has been proposed wherein the width of the grooving groove is measured, and the cutting blade is positioned at the center of the width of the grooving groove, before starting the cutting (see, for example, Japanese Patent No. 5254681). In the case where the center of the groove formed by cutting in such a method (the groove formed by cutting with a cutting blade will hereinafter be referred to as “cut groove”) is positionally deviated from the center of the grooving groove, it is necessary to correct the cutting position at the time of the next cutting operation. For this reason, after cutting by the cutting blade, the width of the cut groove is measured to determine the position of the center of the cut groove, whereby it is checked whether the cut groove has been formed in the center of the grooving groove.